b=1141

b=1141
A reorganization of obdfilter/ before I launch into the real work.
There should be no functional changes.
 - removes unused 'niobuf_remote' argument from fsfilt_brw_start
 - splits filter.c into filter.c, filter_io.c, filter_log.c, and filter_san.c
   More of the same is on the way, but this is a good start.